the present invention relates to exposed aggregate concrete and, more particularly, to an improved non-slick surface-seeded exposed aggregate concrete and method of producing the same.
as is well known, concrete is extensively utilized as a building material for industrial, commercial, and residential applications. Due to its durability, wear resistance and cost economy, concrete has gained widespread use in flooring applications. With this widespread use, Applicants have developed various improvements in concrete flooring products and methods of forming such products. Exemplary improvements include variations in color and surface texture of concrete such that the concrete possesses the aesthetics typical of more costly flooring surfaces such as marble, stone and granite.
In developing innovative improvements to concrete flooring products, Applicants have created many new types of surface-seeded exposed aggregate concrete products and methods of forming the same. Generally, such products are produced by first pouring concrete and then broadcasting or seeding a mass of hard, inert aggregate materials such as sand or gravel over the top surface of the concrete and subsequently troweling the aggregate into the top surface. The aggregate adheres to the concrete and is therefore exposed on the top surface when the concrete cures.
Prior to Applicants' improvements, the surface-seeded exposed aggregate technique required aggregates having a mean size of approximately three-eighths of an inch in diameter or larger. Such large aggregate size was necessary in order to provide sufficient adhesion to the concrete upper cement surface and provide a rough surface to the concrete. Unfortunately, such large aggregate size also limited the widespread use of the technique in flooring applications.
Applicants recognized this deficiency and developed a method to effectively reduce the size of the aggregate exposed on the surface of the concrete, as disclosed in U.S. Pat. No. 4,748,788 entitled “Surface Seeded Exposed Aggregate Concrete and Method of Producing Same” (issued Jun. 7, 1988), hereby incorporated by reference in its entirety. Applicants improved method for producing a decorative slab was comprised of pouring a concrete mixture over a prepared sub grade, finishing the upper surface of the mixture with a bull float, spreading a layer of aggregates less than ⅜ inch in diameter over the mixture, and mixing the two together, applying a chemical retarders, and washing and curing the mixture. The resulting exposed aggregate concrete surface provided improved aesthetics and wear resistance qualities similar to that which is provided by granite, marble or stone flooring.
Applicants later recognized other challenges and developed further improvements to surface-seeded aggregate concrete products. In particular, Applicants developed specific improvements to the above-described technique in Applicants' U.S. Pat. No. 4,748,788. This refined technique, described in Applicants' U.S. Pat. No. 6,016,635, entitled “Surface Seeded Aggregate and Method of Forming the Same” (issued Jan. 25, 2000), facilitated a more uniform top surface texture and greater adhesion of the aggregate thereto and also disclosed the use of glass bead and silica sand as aggregate materials.
Applicants then expanded the variety colors and texture appearances of concrete surfaces produced by the methodology of the surface-seeded exposed aggregate technique of the prior invention. However, one limitation on the variety of surfaces producible was the non-compatibility of certain materials in the concrete mixture. More specifically, scientists reported the occurrence of certain chemical reactions between materials which, over time, degraded the surface. See McConnell et al. “Cement-Aggregate Reaction in Concrete,” J. An. Concrete Inst., V11. 19, No. 2, p. 93 (1947). Siliceous materials found in concrete aggregate were known to react with alkalis in Portland cement, creating siliceous gels which lead to expansion, cracking and exudations upon exposed surfaces.
As a result, concrete specifications now typically limit the alkali content in cement to 0.6% in order to inhibit such reactions in concrete aggregates. Minerals other than silicates found in concrete aggregate appear to react to an insignificant extent and are usually deemed innocuous. In response to these problems, Applicants developed a method of precluding the adverse effects of the potential chemical reactions between desired exposed materials in the concrete mixture which is disclosed in Applicants' U.S. Pat. No. 6,033,146, entitled “Glass Chip Lithocrete and Method of Use of Same” (issued Mar. 7, 2000), hereby incorporated by reference in its entirety.
More recently, additional drawbacks associated with concrete flooring products have come to light in certain high traffic areas where foot gripping and traction are important. Such high traffic areas include stairs, ramps, walkways, courtyards, and the like. In particular, various exposed aggregate concrete products may have a slick surface finish which may be undesirable for these high traffic areas. Although slick surface finishes may usually be safe, materials that form slight surface films, such as liquids, dust, dirt, or other such contaminants may lessen the traction of slick surface finishes. The result is a lack of proper grip or traction, which may cause an individual to slide or slip while walking thereupon.
In order to mitigate the risks associated with slick surface finishes, grip strips or tread strips have been used to increase the traction and friction of such surfaces. For example, adhesive floor friction strips or traction tread flooring have been used to provide additional traction for such surfaces. Adhesive floor friction strips may be adhesively secured to the floor and provide a sandpaper-like finish on an exposed portion thereof to enhance the traction of the floor at the location of the friction strip. Traction tread flooring typically includes a metal panel with small raised perforations which contact the sole of an individual's shoe and create additional grip between the sole and the panel. Various other types of gripping surfaces may be retrofitted onto a completed surface in order to improve the traction and friction generated when walking on the surface. Nevertheless, such materials often decrease the aesthetic appeal of the floors and because they are merely additions to the floor, these materials often become dislodged or peel away from the floor as a result of normal wear and tear.
Thus, there exists a substantial need in the art for an improved exposed aggregate concrete finishing technique which is appropriate for high-pedestrian-traffic flooring applications in that the surface has improved traction. There is a need in the art for an attractive flooring surface that does not require the addition of traction-enhancing materials in order to properly ensure adequate traction and gripping on the surface. Finally, there exists a need in the art for a method of producing such surface-seeded exposed aggregate concrete product that has a non-slick surface finish.